There are many situations in which knowing additional information about a person (or another entity such as a corporation) adds value to a scenario. For example, salary data and a credit score may be needed to determine whether a person is allowed to rent an apartment.
Current location is another piece of additional information that may add value to a scenario. For example, in online and presential (in-person) purchases made with an electronic payment instrument, no cross-check is done on the location of the card owner at the time of the purchase. If an attacker steals the owner's credit card and billing information, there is little evidence to check that the person using the credit card is a legitimate user, particularly in online purchases. Even in presential transactions, checking identifiers (IDs) can be error prone and is not usually done.
However, any time a user provides such additional information, privacy may be lost. In the above example of needing salary/credit score information, a person has to give the information (which may be authorization to get the information) to the landlord/rental company to get approval. Providing location information (other than the location at the time of a presential purchase, which is known) gives the legitimate purchaser an extra layer of protection, but also compromises privacy to an extent. Giving less information yet still getting a desired result in such situations is desirable.